This invention generally relates to high-speed solenoid-operated valves used to control fluid flow and mores specifically to the design of a high-speed solenoid valve used to control intake and exhaust valve movement in an internal combustion engine.
There are many applications for fluid-operated systems that require very fast response and accurate timing. One example of this is intake and exhaust valve actuation in a four-stroke/cycle internal combustion piston engine. Valve actuation has traditionally been accomplished by a cam-operated linkage with a spring used to return each valve to the closed position. Since the timing and duration of the valves are by necessity fixed relative to the crankshaft position, engine operation is compromised. For example, at low speed the intake valve is open too long and some compression pressure is lost by reverse flow out of the intake valve during the compression stroke. By the same token the exhaust valve opens too early, losing some of the effective work that can be accomplished by the combustion gases. At high engine speeds the intake valve closes too early--before the cylinder is completely filled, and the exhaust valve opens too late, leaving residual pressure in the cylinder that has to pumped out during the exhaust stroke. One solution to this problem is to operate the valves with hydraulic power and switch the hydraulic pressure with solenoid valves in response to signals from an engine control computer. However, the hydraulic system has till now suffered from a number of deficiencies. Known hydraulic valves are bulky in size and are limited in flow rate and responsiveness to electrical signals. These limitations reduce the rate at which the engine valves can be opened or closed. Also, solenoid valves with the required force are very heavy and incorporate high-mass moving parts. They also have a very high inductance, requiring high supply voltages to operate at the required speed.
There exists a need for a high speed solenoid valve that is capable of valving high pressure fluid on or off at a high speed without the limitations described above. Such a device can be used, for example, to direct oil to servos used to open and close engine inlet and exhaust valves. The object of this invention is to provide a fast-response, compact valve and low cost valve that is solenoid actuated.
Accordingly, the invention comprises:
A fluid switching valve with a valve member and a stationary member; the valve member containing at least 2 movable valve elements that seat in a first closed position against mating valve seating elements. A cavity formed between the elements is alternatively connected to or isolated from a second cavity by the movement of the valve elements. The valve elements and valve seating elements are made from components that can be precisely matched in thickness and interleaved so that all pairs of elements open and close simultaneously with motion of the valve elements.